1. Technical Field
The present invention relates to a liquid ejecting head, a liquid ejecting head unit and a liquid ejecting apparatus which eject liquid, in particular, to an ink jet recording head, an ink jet recording head unit and an ink jet recording apparatus which discharge ink as liquid.
2. Related Art
As a typical example of a liquid ejecting head, an ink jet recording head which discharges ink droplets from a nozzle opening by utilizing pressure generated by displacement of a piezoelectric element has been known, for example. In the ink jet recording head, a part of a pressure generation chamber communicating with the nozzle opening is constituted by a vibration plate. The vibration plate is deformed by the piezoelectric element so as to apply pressure to ink supplied to the pressure generation chamber. With this, ink droplets are discharged from the nozzle opening.
In such ink jet recording head, if pressure is applied to ink in the pressure generation chamber, a pressure wave is generated in the pressure generation chamber. The pressure wave propagates to a reservoir communicating with the pressure generation chamber. However, unless the pressure wave is attenuated by some way, the pressure wave further propagates to another pressure generation chamber and excellent ink dischargeability cannot be obtained.
Therefore, an ink jet recording head in which a compliance substrate is provided on one surface side of a reservoir and a thin-walled compliance portion is formed has been proposed (for example, see, JP-A-2004-042559). The compliance portion is deformed by pressure fluctuation in the reservoir as an ink chamber which is common to the pressure generation chambers so that energy of the pressure wave is absorbed.
However, if a compliance substrate made of a film or a thin metal plate is provided so as to form a compliance portion, there has arisen a problem that parts processings and assembling are complicated to increase the manufacturing cost. Further, a sufficient effect cannot be obtained unless a compliance portion having a large area to some extent is formed. Therefore, there arises a problem that an apparatus cannot be reduced in size.
Such problems may arise not only in the ink jet recording head but also in liquid ejecting heads which eject liquid other than ink.